1. Field of the Invention
The present invention relates to hydrant security and, more particularly, to a backflow prevention assembly for a fire hydrant for preventing contamination of a municipal water supply.
2. Description of Related Art
Conventional fire hydrants provide a convenient and familiar water outlet, and are typically located throughout communities for fighting fires. Fire hydrants are in fluid communication with water lines, or a municipal water supply, such that they have enough water pressure to rise through the hydrant body and spray outwardly when a valve of the fire hydrant is open. Hydrants are typically located in public areas making them able to be quickly located, and easily accessed by fire fighters, commonly in an emergency. Unfortunately, this accessibility can expose the fire hydrants to unauthorized use or contamination.
Unauthorized use varies. For example, the hydrant can be opened by an unauthorized person in an attempt to contaminate the public water supply by introducing toxins or other dangerous materials into the hydrant, and thus into the water supply. Unauthorized hydrant use can also result in low water pressure throughout the neighborhood or community where the hydrant is located, which could increase the risk of fire damage, due to inadequate water pressure. Clearly, public water safety is an issue that deserves awareness and protection.
A conventional fire hydrant is illustrated in FIG. 1. The fire hydrant 100 includes a barrel 105, which can include both an upper barrel 110 and a lower barrel 120. The fire hydrant 100 can be in communication with a hydrant shoe 130, which is preferably in fluid communication with a water supply 150.
The lower barrel 120, which is commonly referred to as a stand pipe, is connected to the hydrant shoe 130, which is commonly referred to as an elbow, at its lower end 107. The upper end 106 of the lower barrel 120 is connected to the upper barrel 110, which is commonly referred to as a hydrant barrel. The upper barrel 110 is preferably above-ground, making it accessible and easily discoverable for users. To be released from the hydrant, water can flow from the water supply through the hydrant shoe, the barrel, and then outwardly from a nozzle.
The upper barrel 110 includes a nozzle assembly 140, an operating mechanism 160, and a bonnet 170. The nozzle assembly 140 is adapted to allow water to flow out of the hydrant 100. The nozzle assembly 140 includes a nozzle outlet 142, which extends laterally from the upper barrel 110, and a nozzle cap 146. The nozzle outlet 142 can include a nozzle threading 144 and a nozzle opening 148. The nozzle cap 146 is removeable from the nozzle outlet 142 via the nozzle threading 144, enabling the nozzle cap 146 to be attached and removed from the nozzle outlet 142, as needed. If water rises through the upper barrel 110 of the hydrant 100, the water can escape the hydrant 100 via the nozzle opening 148, if the nozzle cap 146 is removed from the nozzle outlet 142.
The operating mechanism 160, which often comprises an operating nut 162, is rotatable, such that a valve assembly 180 can be adjusted to control water flow through the hydrant 100 from the water supply source 150. In many preferred embodiments, the operating nut 162 has a pentagon shape, which may be the same shape as a nut 147 of the nozzle cap 146. By having the same shape, a single tool can be used for both to remove the nozzle cap 146 from the nozzle outlet 142, and for rotating the operating nut 162 to control the valve assembly 180. Although, the pentagon-shape is considered “non-standard” and requires a special wrench, it may also be easily operated with different tools, such as a pipe wrench. This shape can also reduce unauthorized access to an inner cavity of the hydrant 100.
At the lower end of the lower barrel 120 is the valve assembly 180. The valve assembly 180 includes a valve seat 182, a hydrant valve 184, and upper plate 186 and lower plate 188. The valve assembly 180 is adapted to control the water flow through the hydrant 100, for example, to a fire hose connected to the nozzle outlet 142.
An operating stem 190 extends from the valve assembly 180 to the operating nut 162. The operating nut 162 controls the operating stem 190 to open/close the valve assembly 180, as desired or necessary. As the operating nut 162 is rotated, the hydrant valve 184 of the valve assembly 180 can be opened or closed, depending on the direction of the rotation.
As described, the lower end 107 of the lower barrel 120 is in communication with the valve assembly 180. The lower end 107 of the lower barrel 120 is also in communication with the hydrant shoe 130 via a flange 132. The hydrant shoe 130 is connected to the water supply 150.
Having now described a conventional fire hydrant, it is well known to those skilled in the art that hydrants can be tampered with to contaminate water supplying the hydrant. As a result, many conventional solutions for preventing unauthorized persons from having access to the water supply via fire hydrant have been disclosed in U.S. patents. Generally, the solutions can be classified into three separate groups, such as fire hydrant locks, nozzle access prevention, and hydrants containing backflow preventions.
For instance, U.S. Pat. No. 3,935,877 to Franceschi, U.S. Pat. No. 4,566,481 to Leopold, Jr. et al., U.S. Pat. No. 4,842,008 to Avelli et al., and U.S. Pat. No. 5,727,590 to Julicher et al. disclose tamper-proof lock solutions for fire hydrants. That is, each of these patents describes a lock positioned on fire hydrants to prevent unauthorized operation of the hydrant. Unfortunately, each requires different tools to operate the fire hydrant, and cannot be operated by a standard tool, such as a conventional wrench. Thus, if fire fighters do not happen to have the correct tool with them, they cannot access the water supply. As a result, while these solutions attempt to solve problems with preventing access to the water supply, they actually create more problems, and may prevent the desired or necessary access to the water supply, particularly in an emergency.
Nozzle access prevention is disclosed in U.S. Pat. No. 4,182,361 to Oakey, and U.S. Pat. No. 5,383,495 to Kennedy. Both of these patents describe devices that are adapted to prevent unauthorized access into a barrel of a fire hydrant through the hydrant nozzle.
Unfortunately, neither of these approaches is satisfactory. In some instances a special type of hydrant is required, so that it is not possible to apply the locking device to existing hydrants. In other instances, the locking device is designed for the standard hydrant but, because of its complexity, is difficult to operate. In addition, damage to an operating nut and nozzle, or jamming of the protective devices, can be a problem. For instance, vandals can strike the hydrant with a sledgehammer, or other object, to deliver a considerable force, causing the protective device to ultimately break or prevent removal of same during an emergency.
Hydrants containing backflow preventions to prevent access to the water supply are also described in various U.S. patents. For instance, U.S. Pat. No. 3,939,861 to Thompson, U.S. Pat. No. 6,868,860 to Davidson, and U.S. Pat. No. 6,910,495 to Lafalce, are directed to prevent contamination of a municipal water supply with the use of the different types of backflow prevention devices, positioned within the hydrant. Regrettably, the positioning of these backflow prevention devices permit access from the open end of nozzle, which could result in damage, breakage, or even removal of the backflow prevention device. Furthermore, these arrangements are also complex and require precise machining.
What is needed therefore is a hydrant shoe having a backflow prevention assembly that is out of reach of an unauthorized user. It is to such a device that the present invention is primarily directed.